In order to increase its mowing capacity, a lawn mower is provided with a plurality of cutting units. These cutting units are positioned side by side in order to provide the broadest width of work as possible. Each cutting unit comprises rotating blades, a casing in order to stop projectiles thrown by the blades, wheels engaging the ground and eventually an engine to rotate the blades. With all these components, each cutting unit is heavy, and a plurality of heavy cutting units represents an important load.
Gang mowers generally comprise a frame that extends laterally in order to connect the cutting units. The cutting units are mounted on the frame and are articulated between a cutting position and a rest position. Thus, the frame has to bear the weight of cutting units when they are in the rest position. In mowing position, the frame also has to withstand shocks due to unevenness of the ground, or due to curt manoeuvers, or eventually the presence of blocks on the grass forming a hurdle.
The broader the frame is, the higher the frame is strained. For this reason, when the mower comprises a plurality of cutting units, for instance more than ten, the frame needs to be peculiarly resistant. This need of resistance implies to conceive a heavy frame. The frame is mounted on wheels that are configured to bear the weight of the mower, including the weight of the frame, and of cutting units.
The document U.S. Pat. No. 5,076,044 A discloses a mowing device with a frame and a plurality of cutting units. Each cutting unit is linked to the frame by means of chains and lift means. The frame shows an elongated shape and may be pulled by a tractor. The frame is configured in order to be disposed transversally to the drive direction of the tractor. The frame relies on a plurality of pairs of wheels who are distributed along the frame. The wheels engage the ground and bear the weight of the frame. However, these wheels may damage the grass due to their number and to the weight they support. In particular, turf rollers production requires mowing frequently the grass sprout even when they are young and consequently weak. The frequency of passages of the wheels will damage the grass culture and reduce the quality of turf rollers. Damages may be more important when the mower follows curves or turns sharply. For instance, wheels may create some notches on the turf. When the mower turns, the wheels exert shear strains at their interface with the turf. These strains damage the crop.